Photoprotective/cosmetic compositions comprising dibenzoylmethane/triazine/diphenylacrylate compounds

ABSTRACT

Improvedly photostable, topically applicable cosmetic/dermatological sunscreen compositions well suited for enhanced photoprotection of human skin and/or hair against the damaging effects of UV-A and UV-B irradiation, particularly solar radiation, comprise (i) 4-tert-butyl-4′-methoxydibenzoylmethane, (ii) at least one particular 1,3,5-triazine compound, and (iii) at least one alkyl α-cyano-β,β′-diphenylacrylate, formulated in a cosmetically/dermatologically acceptable vehicle, diluent or carrier therefor.

This application is a continuation of application Ser. No. 08/886,245,filed Jul. 1, 1997 now U.S. Pat. No. 5,928,629.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to novel cosmetic and/or dermatologicalcompositions (hereinafter sometimes “antisun” or “sunscreen”compositions) for the photoprocection of the skin and/or the hairagainst UV radiation, in particular solar radiation. More especially,this invention relates to novel cosmetic and/or dermatologicalcompositions exhibiting improved photostability and including, in acosmetically and/or dermatologically acceptable substrate (vehicle,diluent or carrier), the combination of three specific screening agents.

The present invention also relates to the use of the subjectcompositions in the cosmetic and/or dermatological fields.

2. Description of the Prior Art

It is known to this art that light radiation of wavelengths of from 280nm to 400 nm permits the human epidermis to tan and that irradiation ofwavelengths of from 280 nm to 320 nm, i.e., UV-B irradiation, causeserythemas and skin burns which can be harmful to the development of thenatural tan; hence, this UV-B radiation must therefore be screened fromthe skin.

It is also known to this art that UV-A radiation, of wavelengths of from320 nm to 400 nm, which promotes tanning of the skin, also adverselyaffects it, especially in the case of a sensitive skin or of a skinwhich is continually exposed to solar radiation. UV-A rays cause, inparticular, a loss in the elasticity of the skin and the appearance ofwrinkles, promoting a premature aging thereof. Such irradiation promotestriggering of the erythematous reaction or amplifies this reaction incertain individuals and may even be the source of phototoxic orphotoallergic reactions. It is therefore desirable to also filter orscreen out the UV-A radiation.

Thus, for purposes of ensuring protection of the skin and of the hairagainst all of the UV radiation which is as complete as possible and asefficacious as possible, combinations of screening agents which areactive in the UV-A region and of screening agents which are active inthe UV-B region are typically employed in the formulation of sunscreencompositions.

In this respect, 4-tert-butyl-4′-methoxydibenzoylmethane, marketed underthe trademark “Parsol 1789” by Givaudan is a particularly advantageousscreening agent active in the UV-A region, taking account of its highintrinsic absorptivity.

Similarly, 1,3,5-triazine derivatives and in particular,2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine,marketed under the trademark “Uvinul T 150” by BASF, have a highabsorptivity for UV-B radiation. Therefore, it would be veryadvantageous to employ same in combination with the aforementioned4-tert-butyl-4′-methoxydibenzoylmethane with a view towards providingproducts offering wide and efficacious protection throughout the entirerange of UV radiation.

However, it has now been demonstrated that in the presence of4-tert-butyl-4′-methoxydibenzoylmethane and under UV irradiation, theaforesaid 1,3,5-triazine derivatives present the disadvantage of beingextensively degraded chemically. Under these conditions, the combinationof the two screening agents no longer provides a prolonged broadprotection of the skin and of the hair against solar radiation.

SUMMARY OF THE INVENTION

It has now unexpectedly been determined that the formulation of an alkylβ,β′-diphenylacrylate or is alkyl α-cyano-β,β′-diohenylacrylate intocompositions containing 4-tert-butyl-4′-methoxydibenzoylmethane incombination with at least one 1,3,5-triazine derivative, and inparticular with2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine,markedly enhances the stability of such at least one 1,3,5-triazinederivative within such compositions, and hence markedly enhances theoverall effectiveness of these compositions.

Briefly, the present invention features novel cosmetic and/ordermatological compositions comprising, in a cosmetically and/ordermatologically acceptable carrier, diluent or vehicle, (i)4-tert-butyl-4′-methoxydibenzoylmethane, (ii) at least one1,3,5-triazine compound having the following structural formula (I):

wherein X₂ and X₃, which may be identical or different, are each anoxygen atom or the —NH— radical; and R₁, R₂ and R₃, which may beidentical or different, are each a hydrogen atom, an alkali metal, anammonium radical optionally substituted by one or more alkyl orhydroxyalkyl radicals, a linear or branched C₁-C₁₈ alkyl radical, aC₅-C₁₂ cycloalkyl radical optionally ask substituted by one or moreC₁-C₄ alkyl radicals, a polyoxyethylenated radical having from 1 to 6ethylene oxide units and in which the terminal OH group is methylated,or a radical of the following formulae (II), (III) and (IV);

wherein R₄ is hydrogen or a methyl radical, R₅ is a C₁-C₉ alkyl radical,n is an integer ranging from 0 to 3, m is an integer ranging from 1 to10, A is a C₄-C₈ alkyl radical or a C₅-C₉ cycloalkyl radical, B is alinear or branched C₁-C₉ alkyl radical, a C₅-C₈ cycloalkyl radical, oran aryl radical optionally substituted by one or more C₁-C₄ alkylradicals, and R₆ is hydrogen or a methyl radical, and (iii) at least onealkyl β,β′-diphenylacrylate or alkyl α-cyano-β,β′-diphenylacrylatehaving the following structural formula (V):

in which R₇ and R′₇, which may be identical or different, are in a meta-or para-position and are each a hydrogen atom, a straight or branchedchain C₁-C₈ alkoxy radical, or a straight or branched chain C₁-C₄ alkylradical; R₈ is a straight or branched chain C₁-C₁₂ alkyl radical; and R₉is a hydrogen atom or a —CN radical, with the proviso that saidcompositions are devoid of 2-ethylhexyl p-methoxycinnamate.

DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OFTHE INVENTION

More particularly according to the present invention, cosmetic and/ordermatological compositions containing4-tert-butyl-4′-methoxydibenzoylmethane in combination with at least one1,3,5-triazine derivative are provided, in which compositions theconcentration of 1,3,5-triazine compound remains relatively constanteven if the compositions are subjected to the action of light.

Further, the alkyl β,β′-diphenylacrylates or alkylα-cyano-β,β′-diphenylacrylates of the present invention present theadvantage of possessing a good intrinsic screening power whichcontributes to the protection against UV irradiation conferred by thesubject compositions and, in addition, the complete screening system[4-tert-butyl-4′-methoxydibenzoylmethane+1,3,5-triazinederivative+(alkyl β,β′-diphenylacrylate orα-cyano-β,β′-diphenylacrylate)] exhibits overall a very good stabilityunder the action of UV (photostability), which presents anotheradvantage of the compositions according to the invention.

The present invention also features the use of an alkylβ,β′-diphenylacrylate or alkyl α-cyano-β, β′-diphenylacrylate in, or forthe formulation of, cosmetic and/or dermatological compositionscontaining 4-tert-butyl-4′-methoxydibenzoylmethane in combination withat least one 1,3,5-triazine compound as described above with a view toimproving the stability to UV radiation (photostability) of said atleast one 1,3,5-triazine compound in the subject compositions.

This invention also features a process for improving the stability to UVradiation (photostability) and, hence, the effectiveness of a cosmeticand/or dermatological composition comprising4-tert-butyl-4′-methoxydibenzoylmethane and a 1,3,5-triazine compound asdescribed above, in particular2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine, saidprocess entailing incorporating into said composition an effectivephotostabilizing amount of an alkyl β,β′-diphenylacrylate or alkylα-cyano-β,β′-diphenylacrylate.

A first compound of the compositions according to the invention is,therefore, 4-tert-butyl-4′-methoxydibenzoylmethane. This compound is ascreening agent which is per se well known and which has a highabsorptivity in the UV-A region with a maximum at 358 nm. It iscommercially available under the trademark of “Parsol 1789” by Givaudanand has the a following structural formula (VI):

4-Tert-butyl-4′-methoxydibenzoylmethane is advantageously present in thecompositions of the invention in an amount ranging from 0.2% to 15% byweight, relative to the total weight of the composition. This amountpreferably ranges from 0.5% to 10%.

The second compound of the compositions of the present invention is aspecific 1,3,5-triazine compound. The 1,3,5-triazine compounds of thepresent invention are thus selected from among those having thefollowing structural formula (I):

in which X₂ and X₃, which may be identical or different, are each anoxygen atom or the —NH— radical; and R₁, R₂ and R₃, which may beidentical or different, are each a hydrogen atom, an alkali metal, anammonium radical optionally substituted by one or more alkyl orhydroxyalkyl radicals, a linear or branched C₁-C₁₈ alkyl radical, aC₅-C₁₂ cycloalkyl radical optionally substituted by one or more C₁-C₄alkyl radicals, a polyoxyethylenated radical including from 1 to 6ethylene oxide units and in which the terminal OH group is methylated,or a radical of the following formulae (II), (III) and (IV):

wherein R₄ is hydrogen or a methyl radical, R₅ is a C₁-C₉ alkyl radical,n is an integer ranging from 0 to 3, m is an integer ranging from 1 to10, A is a C₄ -C₈ alkyl radical or a C₅-C₈ cycloalkyl radical, B is alinear or branched C₁-C₈ alkyl radical, a C₅-C₈ cycloalkyl radical or anaryl radical optionally substituted by one or more C₁-C₄ alkyl radicals,and R₆ is hydrogen or a methyl radical.

A first, more particularly preferred class of 1,3,5-triazine compoundsis that especially described in EP-A-0 517 104, of the 1,3,5-triazineshaving the above formula (I) and exhibiting all of the followingcharacteristics: X₂ and X₃ are identical and are each an oxygen atom R₁is a C₅-C₁₂ cycloalkyl radical optionally substituted by one or moreC₁-C₄ alkyl radicals, or a radical of formula (II), (III) or (IV) above,in which:

B is a C₁-C₄ alkyl radical,

R₆ is the methyl radical,

R₂ and R₃, which may be identical or different, are each hydrogen, analkali metal, an ammonium radical optionally substituted by one or morealkyl or hydroxyalkyl radicals, a linear or branched C₁-C₁₈ alkylradical, a C₅-C₁₂ cycloalkyl radical optionally substituted by one ormore C₁-C₄ alkyl radicals, or a radical of formula (II), (III) or (IV)above in which:

B is a C₁-C₄ alkyl radical,

R₆ is the methyl radical.

A second preferred class of 1,3,5-triazine compounds according to theinvention is that especially described in EP-A-0 570 838, of the1,3,5-triazines having the formula (I) and exhibiting the combination ofthe following characteristics:

X₃ is the —NH— radical,

R₃ is a linear or branched C₁-C₁₈ alkyl radical, or a C₅-C₁₂ cycloalkylradical optionally substituted by one or more C₁-C₄ alkyl radicals,

R₁ is hydrogen, an alkali metal, an ammonium radical, a radical offormula (IV), a linear or branched C₁-C₁₈ alkyl radical or a C₅-C₁₂cycloalkyl radical optionally substituted by one or more C₁-C₄ alkylradicals, with the provisos that:

if X₂ is the —NH— radical, then R₂ is a linear or branched C₁-C₁₈ alkylradical or a C₅-C₁₂ cycloalkyl radical optionally substituted by one ormore C₁-C₄ alkyl radicals, and

if X₂ is oxygen, then R₂ is hydrogen, an alkali metal, an ammoniumradical, a radical of formula (IV), a linear or branched C₁-C₁₈ alkylradical or a C₅-C₁₂ cycloalkyl radical optionally substituted by one ormore C₁-C₄ alkyl radicals.

A particularly preferred 1,3,5-triazine of this second class is thathaving the following structural formula:

in which R′ is a 2-ethylhexyl radical and R is a tert-butyl radical.

A third preferred class of compounds is that especially described inU.S. Pat. No. 4,724,137, of 1,3,5-triazines having the formula (I) andexhibiting all of the following characteristics:

X₂ and X₃ are identical and are each an oxygen atom,

R₁, R₂ and R₃ are identical and are each a C₆-C₁₂ alkyl radical or apolyoxyethylene radical having from 1 to 6 ethylene oxide units and inwhich the terminal OH group is methylated.

A particularly preferred 1,3,5-triazine of this third class is2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine,which is a screening agent per se known to this art, which is active inthe UV-B region, which is in a solid form and which is commerciallyavailable under the trademark “Uvinul T 150” by BASF. This compound hasthe following structural formula:

in which R′ is a 2-ethylhexyl radical.

The 3,5-triazine derivative(s) is (are) generally present in thecompositions of the invention in an amount that can range from 0.5% to20%, preferably from 1% to 10% by weight, relative to the total weightof the composition.

A third, absolutely essential, compound of the compositions according tothe invention is a compound of the class including alkylβ,β′-diphenylacrylates and alkyl α-cyano-β,β′-diphenylacrylates. Thealkyl β,β′-diphenylacrylates and alkyl α-cyano-β, β′-diphenylacrylatesaccording to the present invention are selected from among those havingthe following structural formula (V):

in which R₇ and R′₇, which may be identical or different, are in a meta-or para-position and are each hydrogen, a straight or branched chainC₁-C₉ alkoxy, or a straight or branched chain C₁-C₄ alkyl radical, R₈ isa straight or branched chain C₁-C₁₂ alkyl radical, and R₉ is a hydrogenatom or a —CN radical.

Among the alkyl β,β′-diphenylacrylates and alkylα-cyano-β,β′-diphenylacrylates according to the present invention, moreparticularly preferred are 2-ethylhexyl α-cyano-β,β′-diphenylacrylateand ethyl α-cyano-β,β′-diphenylacrylate.

2-Ethylhexyl α-cyano-β,β′-diphenylacrylate, also designated octocrylene,is a known lipophilic screening agent absorbing in the UV-B region. Itis available commercially and marketed under the trademark “Uvinul N539” by BASF. It has the following structural formula:

in which φ denotes a phenyl radical.

Ethyl α-cyano-β,β′-diphenylacrylate, also designated etocrylene, is alsoa liposoluble screening agent, absorbing in the UV-B region. It isavailable commercially and marketed under the trademark “Uvinul N 35” byBASF. It has to the following structural formula:

in which φ denotes a phenyl radical.

Thus, when an alkyl β,β′-diphenylacrylate or alkylα-cyano-β,β′-diphenylacrylate is added in sufficient quantity to anantisun or sunscreen composition containing4-tert-butyl-4′-methoxydibenzoylmethane and a 1,3,5-triazine derivativeas described above, an increase in the stability of said 1,3,5-triazinederivative to light is observed and, hence, an improvement in theeffectiveness of the photoprotecting composition over the course oftime.

The alkyl β,β′-diphenylacrylate or alkyl α-cyano-β,β′-diphenylacrylateis preferably present in the compositions according to the invention inan amount of at least 0.5% by weight, relative to the total weight ofthe composition. This amount also preferably ranges from 0.5% to 20% byweight, relative to the total weight of the composition.

The cosmetic and/or dermatological compositions of the present inventionmay, of course, contain one or several additional sunscreens which areactive in the UV-A and/or UV-B region (absorbers) which are hydrophilicor lipophilic, other, naturally, than the three screening agentsindicated above. These additional screening agents are advantageouslyselected from among cinnamic compounds, salicylic compounds, benzylidenecamphor compounds, benzimidazole compounds, triazine compounds otherthan those indicated above, benzophenone compounds,β,β′-diphenylacrylate compounds other than those indicated above,p-aminobenzoic acid compounds and the polymer screening agents andsilicone screening agents described in WO-93/04665. Other examples oforganic screening agents are provided in EP-A 0,487,404.

The compositions according to the invention preferably do not contain2-ethylhexyl p-methoxycinnamate. Indeed, 2-ethylhexyl p-methoxycinnamatecan destabilize compositions comprising4-tert-butyl-4′-methoxydibenzoylmethane and a 1,3,5-triazine compound,such as the subject compositions.

The compositions of this invention may also contain agents forartificial tanning and/or darkening of the skin (self-tanning agents),such as, for example, dihydroxyacetone (DHA).

The cosmetic and/or dermatological compositions of the invention mayfurther contain pigments or nanopigments (primary particle mean sizegenerally ranging from 5 nm to 100 nm, preferably from 10 to 50 nm) ofcoated or uncoated metal oxides such as, for example, nanopigments ofoxide of titanium (amorphous or crystalline in rutile and/or anataseform), of iron, of zinc, of zirconium or of cerium, which are allphotoprotective agents which are per se well known to this art, actingby physical blocking (reflection and/or scattering) of UV radiation.Conventional coating agents are, furthermore, alumina and/or aluminumstearate. Such coated or uncoated metal oxide nanopigments aredescribed, in particular, in EP-A-0,518,772 and EP-A-0,518,773.

The compositions of the present invention may additionally includeconventional cosmetic additives and adjuvants selected, in particular,from among fatty substances, organic solvents, ionic or nonionicthickeners, softeners, antioxidants, agents against anti-free radicalagents, opacifiers, stabilizers, emollients, silicones, α-hydroxyacids,antifoam agents, hydrating agents, vitamins, perfumes, stabilizers,surfactants, fillers, sequestrants, preservatives, polymers,Propellants, alkalifying or acidifying agents, dyes and colorants or anyother ingredient usually employed in the cosmetic and/or dermatologicalfield, in particular for the production of antisun/sunscreencompositions in emulsion form.

The fatty substances may be an oil or a wax or mixtures thereof. By“oil” is intended a compound which is liquid at ambient temperature. By“wax” is intended a compound that is solid or substantially solid atambient temperature, and whose melting point is generally higher than35° C.

Exemplary oils include mineral oils (liquid petrolatum), vegetable oils(sweet almond, macadamia, blackcurrant pip or jojoba oil), syntheticoils such as perhydrosqualene, fatty alcohols, acids or esters (such asthe benzoate of C₁₂-C₁₅ alcohols, marketed under the trademark “FinsolvTN” by Finetex, octyl palmitate, isopropyl lanolate or triglyceridesincluding those of capric/caprylic acids), oxyethylenated oroxypropylenated fatty esters and ethers, siliconated (cyclomethicone,polydimethyl siloxanes or PDMS) or fluorinated oils and polyalkylenes.

Exemplary waxy compounds include paraffin wax, carnauba wax, beeswax andhydrogenated castor oil.

The lower alcohols and polyols are representative of the organicsolvents.

And exemplary thickeners include crosslinked polyacrylic acids, guargums and modified or unmodified celluloses such as hydroxypropylatedguar gum, methyl hydroxyethyl cellulose and hydroxypropyl methylcellulose.

One skilled in this art will, of course, take care to select theaforementioned additional optional compound(s) (in particular theadditional screening agents) and/or their amounts such that theadvantageous properties inherent in the ternary association inaccordance with the invention are not, or are substantially not,adversely affected by the envisaged incorporation(s).

The compositions according to the invention can be prepared viatechniques which are well known to this art, in particular thoseintended for the preparation of emulsions of oil-in-water orwater-in-oil type.

The subject compositions may be formulated in the form of an emulsion,simple or complex (O/W, W/O, O/W/O or W/O/W) such as a cream, a milk, anointment, or in the form of a gel or of a cream gel, of powder, of solidstick and optionally may be packaged as an aerosol and be in the form ofa mousse or spray.

The compositions according to the invention are preferably formulated asoil-in-water emulsions.

When an emulsion, the aqueous phase thereof may include a nonionicvesicular dispersion prepared according to known techniques (Bangham,Standish and Watkins, J. Mol. Biol., 13, 238 (1965), FR-2,315,991 andFR-2,416,008).

The cosmetic and/or dermatological compositions of the invention arewell suited for protecting human skin or hair against the deleteriouseffects of ultraviolet radiation, as antisun compositions or as makeupproducts.

When the cosmetic compositions of this invention are employed for theprotection of human skin against UV rays or as antisun compositions,they may be formulated as suspensions or dispersions in solvents or asfatty substances, in the form of nonionic vesicular dispersions or inthe form of an emulsions, preferably of the oil-in-water type, such as acream or a milk, in the form of salve, gel, cream, ointment, gel, solidstick, stick, aerosol mousse or spray.

When the cosmetic composition according to the invention is employed forprotecting the hair, they may be formulated in the form of shampoo,lotion, gel, emulsion, nonionic vesicular dispersion, hair-fixing sprayand may, for example, constitute a composition to be rinsed away, to beapplied before or after shampooing, before or after dyeing or bleaching,before, during or after permanent waving or straightening, a styling ortreatment lotion or gel, a lotion or gel for blow-drying orhair-setting, or a composition for permanent waving or straightening,dyeing or bleaching the hair.

When the subject compositions are employed as products for making up theeyelashes, the eyebrows or the skin, such as a cream for treating theskin, a foundation, a lipstick, an eye shadow, a blusher, mascara oreyeliner, they may be in anhydrous or aqueous solid or pasty form suchas oil-in-water or water-in-oil emulsions, nonionic vesiculardispersions or suspensions.

By way of example, in the case of antisun/sunscreen formulations inaccordance with the invention which comprise a carrier of theoil-in-water emulsion type, the aqueous phase (including, especially,the hydrophilic screening agents) generally constitutes from 50% to 95%by weight, preferably from 70% to 90% by weight, relative to thecombined formulation, the oily phase (including, especially, thelipophilic screening agents) from 5% to 50% by weight, preferably from10% to 30% by weight, relative to the combined formulation, and the(co)emulsifier(s) constitute from 0.5% to 20% by weight, preferably from2% to 10% by weight, relative to the combined formulation.

The present invention thus also features a cosmetic treatment regime forprotecting the skin and/or the hair against UV radiation, in particularsolar radiation, comprising topically applying thereto an effectivephotoprotecting amount of a cosmetic composition as described above

In order to further illustrate the present invention and the advantagesthereof, the following specific examples are given, it being understoodthat same are intended only as illustrative and in nowise limitative.

EXAMPLES

Four oil-in-water emulsions A, B, C and D were produced, in which thecommon carrier had the following composition (the quantities areexpressed in % of weight relative to the total weight of thecomposition):

(a) 80/20 mixture of cetylstearyl alcohol 7% and of oxyethylenatedcetylstearyl alcohol (33 EO) marketed under the trademark “Dehsconet390” by Tensia (b) mixture of glycerol mono- and distearate 2% marketedunder the trademark “Cerasynth SD” by ISP (c) cetyl alcohol 1.5% (d)polydimethylsiloxanes marketed 1.5% under the trademark “DC 200 Fluid”by Dow Corning (e) benzoate of C₁₂/C₁₅ alcohols, marketed 15% under thetrademark “Finsolve TN” by Finetex (f) ethylenediaminetetraacetic aciddisodium salt, 0.1% 2 H₂O (g) glycerin 20% (h) stabilizers q.s. (i)demineralized water q.s. 100%

The emulsion A (comparative) additionally included a 1,3,5-triazinecompound which was2,4,6-tris[p-(2′-ethylhexyl)-1′oxycarbonyl)anilino]-1,3,5-triazine(Uvinul T 150). Emulsion B, also comparative, contained Uvinul T 150 incombination with 4-tert-butyl-4′-methoxydibenzoylmethane (Parsol 1789).Emulsion C, according to the invention, included, besides Uvinul T 150and Parsol 1789, 2-ethylhexyl α-cyano-β,β′-diphenylacrylate (Uvinul N539). Emulsion D, comparative, contained Uvinul T 150 in combinationwith Parsol 1789, but with a conventional UV-B screening agent which wasoctyl methoxycinnamate (Parsol MCX).

The compositions of the emulsions A, B, C and D with regard to thevarious screening agents indicated above which they contained, arereported in Table I below (the quantities are expressed as weight %relative to the total weight of the composition):

TABLE (I) Emulsion A Emulsion B Emulsion D Screening (compar- (compar-Emulsion C (compar- agent ative) ative) (invention) ative) Uvinul T 1501.5% 1.5% 1.5% 1.5% Parsol 1789 — 0.5% 0.5% 0.5% Uvinul N 539 — —  10% —Parsol MCX — — —  10%

In the case of each of these emulsions, the percentage of residual2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine wasdetermined after irradiation with UV according to the followingprocedure: four control samples and four test samples were prepared inthe case of each formulation. 16 mg of formulation, which was spreadover an area of 2 cm×4 cm, were deposited on depolished PMMA (polymethylmethacrylate) panels rinsed beforehand with water and then dried. Thepanels were then irradiated (Heraeus Suntest CPS) for 4 hours in achamber where the temperature was controlled in the region of 35°-40° C.in order to simulate a natural UV irradiation, the control panels beingstored in the dark during the period of irradiation of the other panels.

The samples were next treated in the following manner: the screeningagents were extracted by immersing each panel in 55 ml of isopropanol inorder to dissolve the screening agents. The panels and the solventcontaining the screening agents were next treated with ultrasonics for 5minutes to ensure an efficient extraction. The solutions obtained wereanalyzed by high performance liquid-phase chromatography.

For each formula tested, the residual proportion of2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine afterirradiation was determined by the ratio of its concentration in theirradiated sample to its concentration in the unirradiated sample.

The results, as percentage of remaining2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine, arereported in the following Table II:

TABLE (II) Emulsion Residual Uvinul T 150 Emulsion A (comparative) 80%Emulsion B (comparative) 68% Emulsion C (invention) 99% Emulsion D(comparative) 79%

While the invention has been described in terms of various preferredembodiments, the skilled artisan will appreciate that variousmodifications, substitutions, omissions, and changes may be made withoutdeparting from the spirit thereof. Accordingly, it is intended that thescope of the present invention be limited solely by the scope of thefollowing claims, including equivalents thereof.

What is claimed is:
 1. A photostable, topically applicablecosmetic/dermatological sunscreen composition suited for theUV-photoprotection of human skin and/or hair, comprising (i) a UV-Aphotoprotecting effective amount of4-tert-butyl-4′-methoxydibenzoylmethane, (ii) a UV-B photoprotectingeffective amount of at least one 1,3,5-triazine compound having thefollowing structural formula (I):

wherein R₁ is a hydrogen atom, an alkali metal or a linear or branchedC₁-C₁₈ alkyl radical, and (iii) a photostabilizing effective amount ofat least one alkyl α-cyano-β,β′-diphenylacrylate having the followingstructural formula (V):

in which R₈ is a linear or branched C₁-C₁₂ alkyl radical.
 2. Thecosmetic/dermatological sunscreen composition as defined by claim 1,formulated into a topically applicable, cosmetically/dermatologicallyacceptable vehicle, diluent or carrier therefor.
 3. Thecosmetic/dermatological sunscreen composition as defined by claim 1,with the proviso that said composition is devoid of destabilizing amountof 2-ethylhexyl p-methoxycinnamate.
 4. The cosmetic/dermatologicalsunscreen composition as defined by claim 1, said at least one1,3,5-triazine compound (I) comprising from 1% to 10% by weight thereof.5. The cosmetic/dermatological sunscreen composition as defined by claim1, said at least one alkyl α-cyano-β,β′-diphenylacrylate (iii)comprising 2-ethylhexyl α-cyano-β,β′-diphenylacrylate or ethylα-cyano-β,β′-diphenylacrylate.
 6. The cosmetic/dermatological sunscreencomposition as defined by claim 1, said at least one alkylα-cyano-β,β′-diphenylacrylate (iii) comprising at least 0.5% by weightthereof.
 7. The cosmetic/dermatological sunscreen composition as definedby claim 6, said at least one alkyl α-cyano-β,β′-diphenylacrylate (iii)comprising from 0.5% to 20% by weight thereof.
 8. Thecosmetic/dermatological sunscreen composition as defined by claim 1,said 4-tert-butyl-4′-methoxydibenzoylmethane (i) comprising from 0.2% to15% by weight thereof.
 9. The cosmetic/dermatological sunscreencomposition as defined by claim 8, said4-tert-butyl-4′-methoxydibenzoylmethane (i) comprising from 0.5% to 10%by weight thereof.
 10. The cosmetic/dermatological sunscreen compositionas defined by claim 1, comprising an oil-in-water emulsion.
 11. Thecosmetic/dermatological sunscreen composition as defined by claim 1,comprising a cream, suspension, gel, milk, cream gel, stick, powder,paste, ointment, lotion, foam, dispersion, mousse or spray.
 12. Thecosmetic/dermatological sunscreen composition as defined by claim 1,comprising a makeup.
 13. The cosmetic/dermatological sunscreencomposition as defined by claim 1, further comprising at least one otherUV-A and/or UV-B screening agent.
 14. The cosmetic/dermatologicalsunscreen composition as defined by claim 1, further comprising at leastone fat, organic solvent, ionic or nonionic thickening agent, softener,antioxidant, anti-free radical agent, opacifying agent, stabilizingagent, emollient, silicone, α-hydroxyacid, anti-foaming agent, hydratingagent, vitamin, fragrance, preservative, surfactant, filler,sequestering agent, polymer, propellant, ossifying or acidifying agent,dye, pigment, colorant, or mixture thereof.
 15. Thecosmetic/dermatological sunscreen composition as defined by claim 1,comprising a shampoo, lipstick, blusher, mascara, eye shadow oreyeliner.
 16. The cosmetic/dermatological sunscreen composition asdefined by claim 1, further comprising a metal oxide pigment ornanopigment.
 17. The cosmetic/dermatological sunscreen composition asdefined by claim 16, comprising an oxide of titanium, zinc iron,zirconium and/or cerium.
 18. The cosmetic/dermatological sunscreencomposition as defined by claim 1, further comprising an artificialtanning active agent.
 19. A regime for protecting human skin and/or hairagainst the deleterious effects of ultraviolet irradiation, comprisingtopically applying thereto an effective UV-photoprotecting amount of thecosmetic/dermatological sunscreen composition as defined by claim
 1. 20.A regime for protecting human skin and/or hair against the deleteriouseffects of solar radiation, comprising topically applying thereto aneffective UV-photoprotecting amount of the cosmetic/dermatologicalsunscreen composition as defined by claim 1.